Used or spent nuclear fuel and radioactive waste materials are presently stored on an interim basis “on site” at commissioned and some decommissioned nuclear generating plants until the federal government provides a central permanent repository. For example, spent nuclear fuel is stored in the reactor fuel pool after removal from the core where it continues to generate decay heat. The fuel can be transferred after a period of cooling in the pool to canisters which are placed in dry storage casks (i.e. overpacks) typically constructed of concrete, steel, and iron, etc. to provide containment and radiation shielding. The casks are stored on site at the generating plant.
The concept of using consolidated interim storage (CIS) is intended to provide geographically distributed off-site storage facilities for spent nuclear fuel and radioactive wastes (collectively “waste”) gathered from a number of individual generating plant sites, thereby providing greater control over the widely dispersed waste stockpiles. The waste materials would initially be transported to the CIS facility from the generating plants for a period of time, with the eventual goal of a final move to a permanent nuclear waste repository when available. Such so called independent spent fuel storage installations (ISFSI) are facilities designed for the interim storage of spent nuclear fuel comprising solid, reactor-related, greater than Class C waste, in addition to other related radioactive materials. Each ISFSI facility would typically maintain an inventor of a multitude of waste canisters containing spent nuclear fuel and/or radioactive waste materials.